"Summon all our people to meet me here as speedily as they can. Call out the giants and the werewolves and the spirits of those trees who are on our side. Call the Ghouls, and the Boggles, the Ogres and the Minotaurs. Call the Cruels, the Hags, the Spectres, and the people of the Toadstools. We will fight..."
-The White Witch, The Lion, The Witch and The Wardrobe (Chapter 13)
Cruels and Hags and Incubuses, Wraiths, Horrors, Efreets, Sprites, Orknies, Wooses, and Ettins. In fact here were all those who were on the witch's side and whom the Wolf had summoned at her command...
-The Lion, The Witch and The Wardrobe (Chapter 14)
If D&D had been less influenced by Tolkien and more by CS Lewis, its bestiary would have looked very different. No goblins or orcs, but plenty of boggles. Evil sprites. Incubuses, ettins, werewolves and efreets as major villains rather than rare encounters. Orknies (meaning nuckelavees?) and wooses (woses?). "Cruels" and "horrors" (whatever they are) running amok - not to mention the people of the Toadstools.
The familiar and iconic entries in the D&D bestiary - orcs, goblins, kobolds, bugbears, ogres and the rest - are really there by fluke. Yes, some were made up by D&D designers. Most weren't, though. They were simply pilfered from other sources. They could just as easily have been overlooked for others in that process. Gary Gygax might have decided not to have orcs, but redcaps, say, and our modern game would be something rather different as a result. (Can you get a half-redcap?)
Want a different tone to your campaign setting and you could do a lot worse than starting off with a copy of the Monstrous Manual and just crossing out and replacing all the iconic monsters and going from there. Redcaps instead of orcs, bogles instead of goblins and nockers instead of dwarves and suddenly it's a different game. Try it with the book or folkloric tradition of your choice and see what you get.